Chitin in the fossil record: identi®cation and quanti®cation of d-glucosamine Matthew B. Flannery a , Andrew W. Stott a,1 , Derek E.G. Briggs b , Richard P. Evershed a, * a Organic Geochemistry Unit, School of Chemistry, Cantock's Close, University of Bristol, BS8 1TS, UK b Department of Earth Sciences, Wills Memorial Building, Queen's Road, University of Bristol, BS8 1RJ, UK Received 7 April 2000; accepted 23 November 2000 (returned to author for revision 1 July 2000) Abstract Although a labile molecule, chitinis resistant todecay whencomplexed withprotein. Currently, qualitative evidence for the preservation of chitin rests upon characteristic marker compounds derived through pyrolysis±gas chromatography± mass spectrometry (Py±GC±MS) of fossil arthropod cuticles, supported by a non-speci®c carbohydrate assay. However, unambiguous con®rmation ofthe survival of chitinpolymer requiresdetection ofits hydrolysatemonomer, d-glucosamine. We have now developed a GC±MS selected ion monitoring (SIM) method for the identi®cation and quanti®cation of d- glucosaminein fossilmaterials. Fossils of various ages anddepositional settings were investigated andthe results compared with those obtained by the Py±GC±MS approach. Specimens from the Rancho La Brea Tar Pits (USA, Pleistocene), showed the greatest degree of preservation: 10% (w/w), while fossil insects from Willershausen (Germany, Pliocene) and St Bauzile (France, Miocene) showed chitin to be present in 5% (w/w). Fossils from the Oligocene at Enspel, Ger- many, revealed that more than 0.5% is preserved for 25 million years. The GC±MS±SIM technique con®rms the survival of chitin in the fossil record through the explicit identi®cation of the polysaccharide monomer, and supports earlier Py±GC± MS and colorimetric analyses. The presence of other amino sugars of either exogenous (microbial) or diagenetic origin in moreancientspecimenswasalsoreadilyrevealedusingtheGC±MS±SIMapproach.Thisstudyillustratesthevalueofusing a high-speci®city quantitative `wet' chemical approach in combination with Py±GC±MS to further advance the inves- tigation of chitin in the fossil record. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Arthropods; Carbohydrate; Chitin; d-Glucosamine; Fossil preservation; Py±GC±MS; GC±MS±SIM 1. Introduction Chitin is one of the most abundant polysaccharides on Earth and occurs in many groups of organisms, princi- pally the arthropods, molluscs, and fungi (Hunt, 1970). The greater part of this chitin, estimated at some 10 11 tons per annum (Gooday, 1990), is rapidly degraded on death of the organisms by enzymatic hydrolysis. Although it is a labile molecule, chitin is relatively resistant to decay when complexed with protein in invertebrate cuticles (Baas et al., 1995). Hence, arthropod cuticle, where histidyl and catechol cross-linking often occurs (Andersen, 1985; Schaefer et al., 1987; Sugumaran, 1988; Hopkins and Kramer, 1992; Kramer et al., 1995), has been observed in the more recent fossil record. Elucidating the diagenesis of biopolymers such as chitin and cellulose sheds light on the wider issue of diagenetic controls on organic materials in the fossil record, and consequently the transformation of these biomolecules to kerogen. Whilst cellulose, the most abundant polysaccharide in the biosphere, has been detected in a variety of sedimentary materials 0146-6380/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0146-6380(00)00174-1 Organic Geochemistry 32 (2001) 745±754 www.elsevier.nl/locate/orggeochem * Corresponding author. Tel.: +44-117-928-7671; fax: +44- 117-929-3746. E-mail address: r.p.evershed@bristol.ac.uk (R.P. Evershed). 1 Present address: ITE Merlewood Research Station, Wind- ermere Road, Grange-over-Sands, Cumbria, LA11 6JU, UK.